Ultraflexible Organic Active Matrix Sensor Sheet for Tactile and Biosignal Monitoring

Abstract

Flexible sensors are currently the subject of intensive research, as they allow cost‐effective and environmentally friendly production of large‐area, flexible, and when fabricated on ultrathin substrates, highly conformable devices. Among many intriguing applications, tactile and biosignal monitoring, where lightweight sensors with high wearing comfort are particularly interesting, is focused on here. The required spatiotemporal resolution of the signals is achieved by integrating the sensors in an active matrix configuration. Organic ferroelectric transducers of high uniformity, characterized, for example, by a sensitivity spread of only 1.5%, are combined with similarly uniform ultralow noise level organic thin film transistors operating below 5 V, showing, for example, a threshold voltage variation of just 0.13 V, in a 12 × 12 sensor array. The transistors transition frequency of up to 160 kHz (saturation range) and 17 kHz (linear range) allows for a high spatiotemporal resolution of ≈3 mm at a frame rate of 1400 fps. The thickness of only 2.8 µm renders the organic active matrix sensor sheet ultraflexible and therefore virtually imperceptible on the human skin. Real‐time monitoring of tactile modes in a subset of 8 × 3 pixels and of the pulse wave including heart rate and blood pressure using four sensors of the matrix is demonstrated.

Flexible resistive tactile pressure sensors

“…This integration involves the utilization of multiple units to produce distinct responses to physical stimuli, thereby allowing the reconstruction of three-dimensional force magnitudes and directions or the spatial distribution of external factors like temperature, humidity, and magnetic field intensity. 164…”

Active-Matrix Array Based on Thin-Film Transistors Using Emerging Materials for Application: From Lab to Industry

“…The high sensitivity of the pressure sensor allows it to detect even minute changes in pressure; so, it can also be applied to biosignal monitoring applications with weak signal strength. Karner-Petritz et al implemented a pressure sensor array, utilizing a poly(vinylidene fluoride: trifluoroethylene) (P(VDF:TrFE))-based ferroelectric transducer and a DNTT-based OTFT for each pixel [98]. They fabricated an organic-based pressure sensor array on a 1 um thick parylene substrate (Figure 6i).…”

“…(i) Schematic diagram of a pressure sensor array in which each pixel consists of a P(VDF:TrFE) ferroelectric transducer and DNTT OTFT. (j) Demonstration of pulse wave measurement by attaching a ferroelectric pressure sensor array to human skin (adapted from [98] with permission from John Wiley and Sons).…”

Research Progress of Vertical Channel Thin Film Transistor Device

“…It was also verified experimentally that after 500 As can be seen in Figure 13, TFT has numerous applications in flexible electronics, including sensing technology, electronic paper, memory, LCD and LED, optoelectronics, and biotechnology. In particular, in sensing technology, TFT can be used in numerous areas of sensors [67][68][69][70][71][72][73][74][75][76][77][78], such as pressure sensors, biosensors, chemical sensors, etc. Next, we will introduce some specific examples of TFT applications in the field of sensors.…”